[Aza-Industries]

Now the game crashed at 5% loading screen. I tried to reinstall from scratch but won't help. . What's wrong ?

Ok I'm not sure but I thought 5% was sound..

If you did this:
1:Install IL-2 1946
2:Install 4.09m Patch
The game should work at this point, if not you may need to re-download the patch (or game if you have the electronic version).
If you want you could then do this
3:Install UP 2.0

That should be a perfect install.

Also when you reinstall stuff make sure to delete the game folder after uninstalling to be sure you got rid of all the files.
UP 2 comes with JSGME and a host of great mods that you can easily install using JSGME including 6dof.
If you do it that way you won't need to do any manual installations.

I'v not tried to install 6dof without UP 2.0 before so I can't really help you there. If you have the inclination to download the HUGE up 2.0 that's your best bet.